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Value of `this` in a node module:

this in NodeJS global scope is the current module.exports object, not the global object. This is different from a browser where the global scope is the global window object. Consider the following code executed in Node:

console.log(this);    // logs {}

module.exports.foo = 5;

console.log(this);   // log { foo:5 }

First we log an empty object because there are no values in module.exports in this module. Then we put foo on the module.exports object, when we then again log this we can see that it now logs the updated module.exports object.

How can we access the `global` object:

We can access the global object in node using the global keyword:

console.log(global);

The global object exposes a variety of useful properties about the environment. Also this is the place where functions as setImmediate and clearTimeout are located.

Answer from Willem van der Veen on Stack Overflow

Node.js

nodejs.org › api › globals.html

Global objects | Node.js v25.8.1 Documentation

This means that var something will define a new global variable, except within ECMAScript modules. In Node.js, this is different. The top-level scope is not the global scope; var something inside a Node.js module will be local to that module, regardless of whether it is a CommonJS module or an ECMAScript module.

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stackoverflow.com › questions › 43627622 › what-is-the-global-object-in-nodejs

What is the 'global' object in NodeJS

Value of `this` in a node module:

this in NodeJS global scope is the current module.exports object, not the global object. This is different from a browser where the global scope is the global window object. Consider the following code executed in Node:

console.log(this);    // logs {}

module.exports.foo = 5;

console.log(this);   // log { foo:5 }

First we log an empty object because there are no values in module.exports in this module. Then we put foo on the module.exports object, when we then again log this we can see that it now logs the updated module.exports object.

How can we access the `global` object:

We can access the global object in node using the global keyword:

console.log(global);

The global object exposes a variety of useful properties about the environment. Also this is the place where functions as setImmediate and clearTimeout are located.

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While in browsers the global scope is the window object, in nodeJS the global scope of a module is the module itself, so when you define a variable in the global scope of your nodeJS module, it will be local to this module.

You can read more about it in the NodeJS documentation where it says:

global

<Object> The global namespace object.

In browsers, the top-level scope is the global scope. That means that in browsers if you're in the global scope var something will define a global variable. In Node.js this is different. The top-level scope is not the global scope; var something inside an Node.js module will be local to that module.

And in your code when you write:

console.log(this) in an empty js file(module) it will print an empty object {} referring to your empty module.
console.log(this); inside a self invoking function, this will point to the global nodeJS scope object which contains all NodeJS common properties and methods such as require(), module, exports, console...
console.log(this) with strict mode inside a self invoking function it will print undefined as a self invoked function doesn't have a default local scope object in Strict mode.

Discussions

How to deal with global variables when modularizing a node.js app?

As much as possible, anything that a function changes should be returned from it rather than modified in place. The purer a function is, the easier it is to test, to reason about, and to compose. Your second best bet if that's impractical is to turn the globals into data attached to the "this" object that your functions are being called as methods on. This still improves your ability to reason about data because it is scoped to a set of functions rather than the whole program. I would caution you against having a giant "context" object that holds all of the mutable globals that you pass around to every function. This is the easiest thing to do when refactoring from a program with lots of globals, but it doesn't actually buy you much over the globals. You're still left with a lot of implicit state that you need to set up before calling each function. More on reddit.com

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May 7, 2016

What is the purpose of the global object in JavaScript?

Pretty much everything is stored in the window object. It's easier to think of the window object as the root object. Whenever you define anything it is either a part of the window object or it is part of another object who has a parent somewhere that is in the window object. More on reddit.com

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July 18, 2018

How to set and access global variables in node.js

Set and export those values from a separate file, just import them wherever needed. Imports are cached, meaning the code in that file will be executed just once. More on reddit.com

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May 31, 2023

Why this is empty in global scope in Nodejs?

Hi, here it's explained: https://stackoverflow.com/questions/43627622/what-is-the-global-object-in-nodejs But in short: The 'global this' is referring to the current module, to itself, which is empty by the time it executes the console.log To access the global object in node, use the global keyword More on reddit.com

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October 18, 2018

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